A new study published in the European Journal of Public Health revealed that the effects of breast cancer screening programs are declining. Why is this happening and what does it mean for the future of breast cancer screenings? 

The good news is that the impact screening mammograms have on mortality rates has decreased in relation to the improvement of cancer treatment. 

"The beneficial effect of screening is currently declining because the treatment of cancer is improving. Over the last 25 years, the mortality rate for breast cancer has been virtually halved," says Henrik Støvring, of the Department of Public Health at Aarhus University, who is also behind the study. 

Stovring notes that there must be a balance between the benefits and harms of screening mammograms, explaining that the exams detect cancer in some women who would have otherwise never known of or felt the effects of the disease during their lifetime, which can lead to both overdiagnosis and overtreatment. 

To better understand the effectiveness of screening mammograms, researchers retrospectively analyzed 10,580 breast cancer deaths among Norwegian women aged 50–75 years from 1986 to 2016. Best case scenarios (5–20% mortality reduction) and overdiagnosis scenarios (10–40% excess breast cancers during screening period) were applied to estimate the ratio of overdiagnosis relative to prevented deaths.